Textbook-Integrated Guide to Educational Resources

TIGER

Using Two-Dimensional Colloidal Crystals To Understand CrystallographyStephanie A. Bosse and Nikolaus M. LoeningDescribes a simple experiment that uses micrometer-sized latex spheres to form two-dimensional colloidal crystals. Diffraction patterns formed by passing a laser beam through these crystals reveal their symmetry and allow the determination of the size of the particles that make up the crystal.Bosse, Stephanie A.; Loening, Nikolaus M. J. Chem. Educ.2008, 85, 93.

Sedimentation Time Measurements of Soil Particles by Light Scattering and Determination of Chromium, Lead, and Iron in Soil Samples via ICPPatricia Metthe Todebush and Franz M. GeigerIn this two-part general chemistry laboratory activity, students study soil samples from home and from campus. In part one, the samples are placed in water and the suspended colloid fraction is separated using filtration, followed by a determination of colloid sedimentation rates via light scattering. In part two, the solid phase of the soil samples is dissolved in acid and analyzed for chromium, lead, and iron using an inductively coupled plasma spectrometer. The experiment can be expanded to include arsenic. Through these experiments students can draw conclusions about the physical and chemical behavior of solid components in soil, paying particular attention to their propensity for transporting and chemically transforming pollutants in the environment. Todebush, Patricia Metthe; Geiger, Franz M. J. Chem. Educ.2005, 82, 1542.

Colloids |

Geochemistry |

Water / Water Chemistry |

Aqueous Solution Chemistry |

Solids |

Surface Science |

Metals

Making Usable, Quality Opaque or Transparent SoapSuzanne T. MabroukFirst-year and organic chemistry students will learn the chemistry of soap by making some of the eleven described formulations, which produce usable, quality bars of soap. Opaque and transparent soaps are made in two and three hours, respectively. With an introduction to formulation chemistry, organic chemistry students can devise a formulation to synthesize their own opaque soap. Many of the formulations use commonly-available fats and oils, while some formulations incorporate specialty fats and oils for therapeutic purposes, for example, to relieve dry skin or itching.Mabrouk, Suzanne T. J. Chem. Educ.2005, 82, 1534.

Our Everyday Cup of Coffee: The Chemistry behind Its MagicMarino PetraccoCoffee beverages are so popular all over the world that there is hardly any need to describe them. But underlying this seemingly commonplace beverage there is a whole realm worth serious scientific study. The complexity of the raw seed matrix, made even more intricate when roasted, requires a deep understanding of its chemical nature. While coffee is not consumed for nutritional purposes, it is appreciated for its taste appeal along with its stimulating effects on mental and physical activity. The attention to quality is of paramount importance to both of these aspects to supply the customers with a pleasant and wholesome product. Petracco, Marino. J. Chem. Educ.2005, 82, 1161.

The Preparation and Testing of a Common Emulsion and Personal Care Product: LotionSuzanne T. MabroukFirst-year chemistry students can readily prepare lotion from the emulsification of deionized water, humectant, emulsifier, emollients, thickener, and preservative. Three different lotion formulations are prepared so that students can study the effects of different emulsifiers and emollients on the quality of the final product. The purpose of the ingredients is discussed. Mabrouk, Suzanne T. J. Chem. Educ.2004, 81, 83.

Demonstration of Surface TensionAndrew J. RosenthalEven though surface tension is a tensor with a relatively small magnitude, when it acts on particles with a small radius, the overall force produced is substantial. Surface tension is responsible for the destabilization of many colloidal systems. This short paper describes a simple demonstration that illustrates the phenomenon. Rosenthal, Andrew J. J. Chem. Educ.2001, 78, 332.

Colloids |

Food Science |

Industrial Chemistry |

Surface Science

Preparation and Properties of an Aqueous FerrofluidPatricia Enzel, Nicholas B. Adelman, Katie J. Beckman, Dean J. Campbell, Arthur B. Ellis, and George C. LisenskyThis paper describes a simple synthesis of an aqueous-based ferrofluid that may be used in an introductory science or engineering laboratory. This paper also describes a method for repelling both oil- and water-based ferrofluid from solid surfaces that would otherwise be stained by the fluid. Finally, a demonstration of the interaction between ferrofluid and magnetic fields, in which ferrofluid is induced to leap upward by a stack of magnets, is described. Enzel, Patricia; Adelman, Nicholas B.; Beckman, Katie J.; Campbell, Dean J.; Ellis, Arthur B.; Lisensky, George C. J. Chem. Educ.1999, 76, 943.

Materials Science |

Magnetic Properties |

Nanotechnology |

Stoichiometry |

Colloids

Showing Emulsion Properties with Common Dairy FoodsCarlos Bravo-Diaz and Elisa Gonzalez-RomeroFood emulsions cover an extremely wide area of life applications such as milk, sauces, dressings and beverages. Experimentation with some culinary recipes allows a discussion of the nature and composition of foods, and the effects of additives. At the same time it allows insight into the scientific reasoning that underlie the recipes. J. Chem. Educ.1996, 73, 844.

Appetizing colloidsRiley, John T.Two examples of colloidal dispersions: the formation of foam upon mixing a solution of aluminum sulfate with a solution of egg albumin and sodium bicarbonate, and the formation of a gel upon mixing ethanol with a saturated solution of calcium acetate.Riley, John T. J. Chem. Educ.1980, 57, 153.

Determination of Avogadro's number by Perrin's lawSlabaugh, W. H.The experimental procedure for determining Avogadro's number by the Perrin method includes preparing a monodisperse colloid, ascertaining the mass of the particles, and making an accurate count of the number of particles at two points in the equilibrated colloid.Slabaugh, W. H. J. Chem. Educ.1965, 42, 471.

Stoichiometry |

Kinetic-Molecular Theory |

Gases |

Colloids

The use of colloidal graphite for laboratory demonstrationsSmith, Edward A.Examines the shape of graphite particles, the electrical properties of colloids, the coagulation of colloids, graphite and magnetic orientation, and the electrical conductivity of graphite.Smith, Edward A. J. Chem. Educ.1956, 33, 600.

Colloids |

Conductivity |

Magnetic Properties

Textbook errors: II. Brownian motion and the stability of colloidsMysels, Karol J.The fact that colloidal solutions are frequently quite stable and their particles do not sediment when kept in bottles under normal laboratory conditions is frequently attributed the incessant agitation of Brownian motion.Mysels, Karol J. J. Chem. Educ.1955, 32, 319.